How to notify other group when same group submit entry?

Sorry for my English..

Here the situation.

Let say I've set up a 2 groups. Group 1 (male) , Group 2 (female)
And these 2 groups has a few type of interest e.g : CAR, TRAVEL and HEALTH

Then when user of Group 1 submit a post related to CAR, other users related to CAR (Group 2) can notify those post with private message or email.

So how to implement this project and what modules is related?

I hope somebody can help me..

Thanks..

p/s: sorry if hard to understand my English.